1. Field of the Invention
The present invention relates to a ceramic electronic device and its producing method and more specifically, to advanced ceramic devices including a filter for eliminating noise in a digital circuit, a high-brid IC, a multi-layer device, a printed circuit tip, and an arrayed thick-film device such as a high-frequency filter, and their producing methods.
2. Description of the Prior Art
For producing tip-type or array-type ceramic electrode devices of smaller size and higher quality including a high-brid IC, a multi-layer ceramic device, a printed circuit tip, and a composite thick-film device such as a filter, a process has been introduced in which the internal electrodes are built in multiple layers by layer printing and connected via through or bare holes to the external electrodes which are formed by through-hole printing.
The conventional process will be described referring to FIGS. 53 to 55 in which external electrodes are formed by through-hole printing in the apertures arranged in a ceramic substrate for producing a given number of array-type tip resistors. FIG. 53 is a perspective view of an array-type tip resistor in which provided are a ceramic base 1a, resistors 2, electrode extensions 3, and external electrodes 4. The electrode extensions 3 are formed by printing on the resistors 4 and connected to the external electrodes 4 formed by through-hole printing.
FIG. 54 is a perspective view explaining a step of the conventional process in which the resistors 2 are distributed on a ceramic substrate 1b. The ceramic substrate 1b is provided with a given pattern of score lines 5 and rows of apertures 6 extending across and along the score lines 5.
FIG. 55 is a perspective view of showing another step of the process in which the electrode extensions 3 coupled to the resistors 2 allocated at the step of FIG. 54. More particularly, a material ink of the electrode extension 3 is printed between the two adjacent resistors 2, 2 and before the ink is dried, its portion is drawn in by suction through the aperture 6 from the below of the ceramic substrate 1b so that the electrode extension 3 is elongated. Hence, the inner wall of the aperture 6 of the ceramic substrate 1b is covered with a uniform thickness of the electrode extension 3 (as the result of the through-hole printing).
The ceramic substrate 1b having the electrode extensions 3 of the electrode ink extending in its apertures 6 and connected to the resistors 2 is baked at a given temperature and cut along the score lines 5 into the array-type tip resistors shown in FIG. 53. At the time, the electrode ink material distributed into each aperture 6 is also separated into two and becomes the external electrode 4 of the array-type tip resistor as shown in FIG. 53.
This through-hole printing technique has widely be used for production of common or high-brid circuit boards. Also, a variety of processes have been developed for carrying out the application or distribution of material ink to the inner wall of the apertures,
As described previously, each aperture 6 of the ceramic substrate 1b has to spare a margin of unoccupied surface around its location when it is used for implementation of the through-hole printing of an electrode material ink by suction or to accept the external electrode 4 printed down. This restricts the arrangement of other circuits close to and about the aperture 5. When multi-layer ceramic circuits are disposed on a ceramic substrate 1b, no external electrode can be built by the through-hole printing without giving a specific protection.
More particularly, when a dielectric or magnetic material is distributed next to the aperture of the ceramic substrate, its portion tends to flow into the aperture and reduce the cross area of the same or if worse, close up the aperture. As the result, when a stream of air is developed by suction in the aperture for the through-printing, its velocity varies due to ununiformity of the cross area causing a dope of the ink to run irregularly. This results in undulation of the coating of the ink on the inner wall of the aperture. Thus, it hardly is possible to apply or impress any other material close to the apertures on the ceramic substrate when the apertures of the ceramic substrate are used for implementation of the through-hole printing or to accept the external electrodes printed down. Accordingly, it will be difficult to reduce the size of the ceramic electronic device produced by placing a ceramic layers structure on such a ceramic substrate using the conventional process.